KR20200079847A - Composition for polishing pad, polishing pad and preparation method thereof - Google Patents

Abstract

In a composition according to an embodiment, a content of unreacted NCO groups and a content of unreacted aromatic diisocyanate monomers in a urethane-based prepolymer can be adjusted to control physical properties such as gelation time. Therefore, since a polishing pad obtained by curing the composition according to the embodiment can control fine pore characteristics, a polishing rate, and a pad cutting rate, a high quality semiconductor device can be efficiently prepared using the polishing pad.

Description

Composition for polishing pad, polishing pad, and manufacturing method thereof{COMPOSITION FOR POLISHING PAD, POLISHING PAD AND PREPARATION METHOD THEREOF}

Embodiments relate to a composition for a porous polyurethane polishing pad, a porous polyurethane polishing pad, and a method for manufacturing the same, which can be used in a chemical mechanical planarization (CMP) process of semiconductors.

During the semiconductor manufacturing process, the chemical mechanical planarization (CMP) process chemically polishes the wafer surface by supplying a slurry while attaching the wafer to the head and making contact with the surface of the polishing pad formed on the platen. It is a process of mechanically flattening the uneven portion of the wafer surface by reacting the platen and head while reacting.

The polishing pad is an essential raw material that plays an important role in the CMP process, and is generally made of a polyurethane resin, and the polyurethane resin includes a prepolymer, a curing agent, and a foaming agent obtained by reacting a diisocyanate monomer with a polyol. do.

In addition, the polishing pad is provided with a groove that is responsible for a large flow of slurry on the surface and a pore that supports fine flow, and the pore uses a solid foaming agent having an air gap, an inert gas, liquid material, fiber, and the like. Or by generating a gas by a chemical reaction.

Korea Patent Publication No. 2016-0027075

The urethane-based prepolymer used to manufacture the polishing pad changes physical properties depending on the monomer, which greatly affects the performance of the chemical mechanical planarization (CMP) process. Therefore, controlling the composition and physical properties of the urethane-based prepolymer is very important in controlling the performance of the polishing pad.

As a result of the research conducted by the present inventors, the gelation time is also changed by the content of unreacted NCO groups and the content of unreacted aromatic dicyanate monomers present in the urethane-based prepolymer, and accordingly, the elongation and pore size of the polishing pad It has been found that changes affect CMP performance such as the polishing rate.

Therefore, the embodiments, the composition to control the physical properties by adjusting the content of the unreacted NCO group and the content of unreacted aromatic diisocyanate monomer in the urethane-based prepolymer, a method for manufacturing a polishing pad using the same, polishing obtained from the composition It is intended to provide a pad and a method of manufacturing a semiconductor using the polishing pad.

According to one embodiment, a urethane-based prepolymer, a curing agent and a blowing agent, the urethane-based prepolymer includes at least one diisocyanate monomer and at least one polyol prepolymerization reaction product, and the at least one diisocyanate monomer is It includes one or more aromatic diisocyanate monomers, and the urethane-based prepolymer contains 5% to 13% by weight of unreacted NCO groups based on the weight of the urethane-based prepolymer, and unreacted aromatic diisocyanate monomers. The composition is provided, comprising 0.1 to 5% by weight.

According to another embodiment, preparing a first raw material composition comprising a urethane-based prepolymer; Preparing a second raw material composition comprising a curing agent; Preparing a third raw material composition comprising a blowing agent; Preparing the raw material mixture by sequentially or simultaneously mixing the first raw material composition with the second raw material composition and the third raw material composition; And injecting the raw material mixture into a mold to cure the urethane-based prepolymer, which has the same configuration as the urethane-based prepolymer included in the composition according to one embodiment, and provides a method for manufacturing a polishing pad.

According to another embodiment, the polyurethane resin and a plurality of fine pores dispersed in the polyurethane resin, the polyurethane resin is derived from a urethane-based prepolymer, the urethane-based prepolymer according to one embodiment above A polishing pad having the same configuration as the urethane-based prepolymer included in the composition is provided.

According to another embodiment, the step of polishing the surface of the wafer using a polishing pad, the polishing pad comprises a polyurethane resin and a plurality of fine pores dispersed in the polyurethane resin, the polyurethane resin Is derived from a urethane-based prepolymer, and the urethane-based prepolymer has the same configuration as the urethane-based prepolymer included in the composition according to one embodiment, and a method for manufacturing a semiconductor device is provided.

The composition according to the embodiment can be controlled by controlling the content of the unreacted NCO group and the content of the unreacted aromatic diisocyanate monomer in the urethane-based prepolymer, such as gelation time.

Therefore, the polishing pad obtained by curing the composition according to the embodiment can be controlled to fine pore characteristics, polishing rate and pad cutting rate, it is possible to efficiently manufacture a high-quality semiconductor device using the polishing pad.

1A, 1B, and 1C are scanning electron microscope (SEM) images of pores of the polishing pads of Examples 1, 2, and 1, respectively.
Figure 2 shows the polishing rate (removal rate) of the polishing pad of Example 1, Example 2 and Comparative Example 1.
Figure 3 shows the pad cut rate (pad cut rate) of the polishing pad of Example 1, Example 2 and Comparative Example 1.

In the description of the following embodiments, when each layer, pad, sheet, or the like is described as being formed "on" or "under" of each layer, pad, or sheet, the "phase ( "on"" and "under" include both "directly" or "indirectly".

In addition, the criteria for the top and bottom of each component will be described based on the drawings. The size of each component in the drawings may be exaggerated for explanation, and does not mean the size actually applied.

In addition, it should be understood that all numerical ranges representing physical property values, dimensions, and the like of the components described in the present specification are modified with the term "about" in all cases unless otherwise specified.

[Composition for polishing pads]

The composition according to one embodiment includes a urethane-based prepolymer, a curing agent, and a blowing agent, and the urethane-based prepolymer includes a prepolymerization reaction product of at least one diisocyanate monomer and at least one polyol, and the at least one diisocyanate The monomer includes one or more aromatic diisocyanate monomers, and the urethane-based prepolymer contains 5% to 13% by weight of unreacted NCO groups based on the weight of the urethane-based prepolymer, and unreacted aromatic di Isocyanate monomer is contained in an amount of 0.1 to 5% by weight.

Urethane prepolymer

A prepolymer generally means a polymer having a relatively low molecular weight in which the polymerization degree is stopped in an intermediate step so as to be easily molded in manufacturing a final molded article. For example, the weight average molecular weight (Mw) of the urethane-based prepolymer may be 500 g/mol to 3,000 g/mol, 600 g/mol to 2,000 g/mol, or 700 g/mol to 1,500 g/mol. The prepolymer can be formed as a final product by itself or after reacting with other polymerizable compounds or curing agents.

The urethane-based prepolymer is a prepolymerization reaction product of at least one diisocyanate monomer and at least one polyol.

The one or more diisocyanate monomers may be one or more aromatic diisocyanate monomers and/or one or more aliphatic diisocyanate monomers, for example, toluene diisocyanate (TDI), naphthalene-1,5-di Isocyanates (naphthalene-1,5-diisocyanate), para-phenylene diisocyanate, tolidine diisocyanate, diphenylmethane diisocyanate (MDI), hexamethylene diisocyanate ( It may be at least one isocyanate selected from the group consisting of hexamethylene diisocyanate (HDI), dicyclohexylmethane diisocyanate (H12MDI), isophorone diisocyanate, and the like.

As a specific example, the one or more diisocyanate monomers include one or more aromatic diisocyanate monomers, and the one or more aromatic diisocyanate monomers include toluene 2,4-diisocyanate and toluene 2,6-diisocyanate. Can.

As another specific example, the at least one diisocyanate monomer further includes at least one aliphatic diisocyanate monomer, and the at least one aliphatic diisocyanate monomer is diphenylmethane diisocyanate (MDI), hexamethylene diisocyanate (HDI). , Dicyclohexylmethane diisocyanate (H12MDI).

Chain composition in the prepolymer

The urethane-based prepolymer includes polymerization reactants of various molecular weights between a diisocyanate monomer and a polyol.

For example, in the urethane-based prepolymer, the diisocyanate monomer may constitute a chain in the prepolymer by at least one NCO group being urethane-reacted (ie, two NCO groups are urethane-reacted or one NCO group is urethane-reacted). .

In the present specification, the urethane reaction means that the NCO group of the diisocyanate monomer reacts with the OH group of the polyol to form a urethane group to be connected.

In particular, the at least one diisocyanate monomer used in the preparation of the urethane-based prepolymer includes at least one aromatic diisocyanate monomer, and such at least one aromatic diisocyanate monomer may be involved in a prepolymerization reaction at a high rate.

For example, the urethane-based prepolymer, based on the total weight of the at least one aromatic diisocyanate monomer, at least one NCO group urethane-reacted aromatic diisocyanate monomer is 50% to 99% by weight, 60% to 60% by weight 99 wt%, 70 wt% to 99 wt%, 80 wt% to 99 wt%, or 90 wt% to 99 wt%.

In particular, the urethane-based prepolymer, based on the total weight of the at least one aromatic diisocyanate monomer, two NCO groups urethane-reacted aromatic diisocyanate monomer is 10% by weight to 40% by weight, 10% by weight to 35% by weight , 15 wt% to 35 wt%, 20 wt% to 35 wt%, 10 wt% to 30 wt%, 20 wt% to 30 wt%, or 10 wt% to 25 wt%.

As a specific example, the urethane-based prepolymer, based on the total weight of the one or more aromatic diisocyanate monomers, may include the aromatic diisocyanate monomer reacted with the two NCO groups urethane at 25% to 35% by weight. .

In addition, the urethane-based prepolymer, based on the total weight of the one or more aromatic diisocyanate monomers, 50% to 90% by weight, 60% to 90% by weight of an aromatic diisocyanate monomer in which one NCO group is urethane-reacted , 70% to 90% by weight, 80% to 90% by weight, 50% to 80% by weight, or 60% to 80% by weight.

As a specific example, the urethane-based prepolymer, based on the total weight of the one or more aromatic diisocyanate monomers, may include 50 to 80% by weight of an aromatic diisocyanate monomer in which one NCO group is urethane-reacted.

At this time, the urethane-based prepolymer is a weight ratio of 0.1 to 1 to 1:1 by weight ratio of the aromatic diisocyanate monomer to which the two NCO groups are urethane-reacted, and the one to which the NCO group is urethane-reacted, from 0.2 to 1 to 1:1. The weight ratio, 0.2: 1 to 0.5: 1 weight ratio, 0.3: 1 to 1:1 weight ratio, or 0.3: 1 to 0.5: 1 weight ratio.

As a specific example, the urethane-based prepolymer may include the aromatic diisocyanate monomer in which the two NCO groups are urethane-reacted, and the aromatic diisocyanate monomer in which the one NCO group is urethane-reacted in a weight ratio of 0.2:1 to 0.5:1. .

More specifically, the at least one aromatic diisocyanate monomer may include toluene 2,4-diisocyanate and toluene 2,6-diisocyanate, wherein the urethane-based prepolymer is a total of the at least one aromatic diisocyanate monomer. 80 to 98% by weight to 85 to 85% by weight of at least one NCO group urethane-reacted toluene 2,4-diisocyanate and at least one NCO group urethane-reacted toluene 2,6-diisocyanate 98 wt%, 90 wt% to 98 wt%, 93 wt% to 98 wt%, or 95 wt% to 98 wt%.

In addition, the urethane-based prepolymer, based on the total weight of the at least one aromatic diisocyanate monomer, two NCO groups urethane-reacted toluene 2,4-diisocyanate 10 to 40% by weight, 10% to 10% by weight 35 wt%, 15 wt% to 35 wt%, 20 wt% to 35 wt%, 10 wt% to 30 wt%, 20 wt% to 30 wt%, or 10 wt% to 25 wt%.

As a specific example, the urethane-based prepolymer, based on the total weight of the one or more aromatic diisocyanate monomers, comprises 2 to 10% by weight to 30% by weight of toluene 2,4-diisocyanate with two NCO groups urethane-reacted Can.

In addition, the urethane-based prepolymer, based on the total weight of the one or more aromatic diisocyanate monomers, 40 to 80% by weight, 45% to 45% by weight of toluene 2,4-diisocyanate with one NCO group urethane-reacted 75 wt%, 45 wt% to 70 wt%, 45 wt% to 65 wt%, 45 wt% to 60 wt%, 60 wt% to 75 wt%, or 60 wt% to 70 wt%.

As a specific example, the urethane-based prepolymer, based on the total weight of the one or more aromatic diisocyanate monomers, one NCO group may contain 50 to 65% by weight of toluene 2,4-diisocyanate with urethane reaction Can.

In addition, the urethane-based prepolymer, based on the total weight of the one or more aromatic diisocyanate monomers, 1 NCO group urethane-reacted toluene 2,6-diisocyanate 1 wt% to 30 wt%, 5 wt% to 25 wt%, 10 wt% to 25 wt%, 10 wt% to 20 wt%, 5 wt% to 20 wt%, 5 wt% to 15 wt%, or 10 wt% to 15 wt%.

As a specific example, the urethane-based prepolymer, based on the total weight of the one or more aromatic diisocyanate monomers, may contain 10 to 20% by weight of toluene 2,4-diisocyanate with one NCO group urethane-reacted Can.

Unreacted diisocyanate monomer

In addition, some of the compounds used in the reaction for the preparation of the urethane-based prepolymer may not be involved in the reaction.

Therefore, a compound remaining without being involved in the reaction may be present in the urethane-based prepolymer.

Specifically, the urethane-based prepolymer may include unreacted diisocyanate monomer. In the present specification,'unreacted diisocyanate monomer' means a diisocyanate monomer in which both NCO groups remain unreacted.

The urethane-based prepolymer, based on the weight of the urethane-based prepolymer, the unreacted diisocyanate monomer is 7% by weight to 10% by weight, 7% by weight to 9% by weight, 7% by weight to 8% by weight, 8% by weight It may include from 10 to 10% by weight, 8.5% to 10% by weight, 9% to 10% by weight, and 8% to 9% by weight.

The unreacted diisocyanate monomer present in the urethane-based prepolymer may include unreacted aromatic diisocyanate monomer.

For example, the urethane-based prepolymer, based on the weight of the urethane-based prepolymer, 0.1% to 5% by weight of unreacted aromatic diisocyanate monomer, 0.1% to 3% by weight, 0.1% to 2.3% by weight %, 0.1% to 1.5%, 0.1% to 1%, 0.5% to 2%, 1% to 2%, 1% to 3%, or 1% to 5% It can contain as.

As a specific example, the urethane-based prepolymer, based on the weight of the urethane-based prepolymer, may include 1% to 3% by weight of unreacted aromatic diisocyanate monomer.

When one or more aromatic diisocyanate monomers used in the reaction of the urethane-based prepolymer include toluene 2,4-diisocyanate and toluene 2,6-diisocyanate, of which toluene 2,6-diisocyanate is relatively reactive Since it is low, it may be present in the urethane-based prepolymer without reacting with the polyol.

For example, the urethane-based prepolymer, based on the weight of the urethane-based prepolymer, the unreacted toluene 2,6-diisocyanate is 0.1% to 10% by weight, 0.1% to 8% by weight, 0.1% by weight to 6 wt%, 0.1 wt% to 4 wt%, 0.5 wt% to 4 wt%, or 1 wt% to 4 wt%.

As a specific example, the urethane-based prepolymer may include unreacted toluene 2,6-diisocyanate in an amount of 0.1 to 3% by weight based on the weight of the urethane-based prepolymer.

In addition, the unreacted diisocyanate monomer present in the urethane-based prepolymer may include an unreacted aliphatic diisocyanate monomer.

For example, the urethane-based prepolymer, based on the weight of the urethane-based prepolymer, 1 wt% to 20 wt%, 1 wt% to 15 wt%, 1 wt% to 10 wt% of unreacted aliphatic diisocyanate monomer %, 5% to 20% by weight, 10% to 20% by weight, or 5% to 15% by weight.

In addition, the urethane-based prepolymer has an unreacted aromatic diisocyanate monomer and an unreacted aliphatic diisocyanate monomer in a weight ratio of 0.01:1 to 1:1, a weight ratio of 0.05:1 to 0.8:1, and a 0.05:1 to 0.5:1. Or, it may be included in a weight ratio of 0.05:1 to 0.3:1.

As a specific example, the urethane-based prepolymer may include unreacted aromatic diisocyanate monomer and unreacted aliphatic diisocyanate monomer in a weight ratio of 0.05:1 to 0.7:1.

Unreacted NCO group content

The urethane-based prepolymer may have an unreacted NCO group at the end of the polymer, oligomer or monomer contained therein.

As a specific example, the urethane-based prepolymer, based on the weight of the urethane-based prepolymer, 5% to 13% by weight of unreacted NCO groups, 5% to 10% by weight, 7% to 13% by weight, 7 It may include a weight% to 10% by weight, 7.5% to 10% by weight, 9% to 11% by weight, or 9% to 10% by weight.

As a specific example, the urethane-based prepolymer may include 7% to 10% by weight of the unreacted NCO group based on the weight of the urethane-based prepolymer. At this time, the urethane-based prepolymer, based on the weight of the urethane-based prepolymer, may include the unreacted aromatic diisocyanate monomer in 1% to 3% by weight. In addition, the composition may have a gelation time of 100 seconds to 115 seconds.

Polyol

The polyol refers to a compound having two or more hydroxyl groups, and may include a monomolecular polyol and a polymer polyol.

Examples of the monomolecular type polyol include ethylene glycol (EG), diethylene glycol (DEG), propylene glycol (PG), propanediol (PDO), methyl propanediol (MP-diol), and the like, and the polymer type Examples of polyols include polyether polyols, polyester polyols, polycarbonate polyols, polycarprolactone polyols, and the like. The polymer-type polyol may have a weight average molecular weight of 300 g/mol to 3,000 g/mol.

Hardener

The curing agent may be at least one of an amine compound and an alcohol compound. Specifically, the curing agent may include at least one compound selected from the group consisting of aromatic amines, aliphatic amines, aromatic alcohols, and aliphatic alcohols.

For example, the curing agent is 4,4'-methylenebis (2-chloroaniline) (MOCA), diethyltoluenediamine (DETDA), diaminodiphenyl methane, diaminodiphenyl methane, diaminodiphenyl sulfone ( diaminodiphenyl sulphone, m-xylylene diamine, isophoronediamine, ethylenediamine, diethylenetriamine, triethylenetetramine, polypropylenediamine ), polypropylenetriamine, ethyleneglycol, diethyleneglycol, dipropyleneglycol, butanediol, hexanediol, glycerine, trimethylolpropane ( trimethylolpropane) and bis(4-amino-3-chlorophenyl)methane.

The urethane-based prepolymer and curing agent may be mixed in a molar equivalent ratio of 1:0.8 to 1:1.2, or a molar equivalent ratio of 1:0.9 to 1:1.1, based on the number of moles of reactive groups in each molecule. . Here, the term "based on the number of moles of each reactive group" means, for example, based on the number of moles of the isocyanate group of the urethane-based prepolymer and the number of moles of the reactive groups (amine group, alcohol group, etc.) of the curing agent. Therefore, the urethane-based prepolymer and the curing agent may be introduced at a constant rate in the mixing process, so that the input rate is adjusted to be injected per unit time in an amount satisfying the molar equivalent ratios exemplified above.

blowing agent

The foaming agent is not particularly limited as long as it is commonly used to form pores in the polishing pad.

For example, the blowing agent may be at least one selected from solid blowing agents having a hollow structure, liquid blowing agents using volatile liquids, and inert gases.

The solid foaming agent may be a microcapsule (hereinafter referred to as a'thermoexpanded microcapsule') that is thermally expanded and sized. The thermally expanded microcapsules may be obtained by thermally expanding the thermally expandable microcapsules. The thermally expanded microcapsule has the advantage of being able to uniformly adjust the size of the pores by having a uniform sized particle diameter as a structure of the already expanded microballoon. Specifically, the solid foaming agent may be a micro balloon structure having an average particle diameter of 5 μm to 200 μm.

The thermally expandable microcapsule includes an outer shell comprising a thermoplastic resin; And a foaming agent encapsulated inside the shell. The thermoplastic resin may be at least one selected from the group consisting of a vinylidene chloride-based copolymer, an acrylonitrile-based copolymer, a methacrylonitrile-based copolymer and an acrylic copolymer. Furthermore, the blowing agent may be at least one selected from the group consisting of hydrocarbons having 1 to 7 carbon atoms.

The solid blowing agent may be used in an amount of 0.1 to 2.0 parts by weight based on 100 parts by weight of the urethane-based prepolymer. Specifically, the solid blowing agent may be used in an amount of 0.3 parts by weight to 1.5 parts by weight, or 0.5 parts by weight to 1.0 part by weight based on 100 parts by weight of the urethane-based prepolymer.

The inert gas is not particularly limited as long as it is a gas that does not participate in the reaction between the urethane-based prepolymer and the epoxy curing agent. For example, the inert gas may be at least one selected from the group consisting of nitrogen gas (N ₂ ), carbon dioxide gas (CO ₂ ), argon gas (Ar), and helium (He). Specifically, the inert gas may be nitrogen gas (N ₂ ) or carbon dioxide gas (CO ₂ ).

The inert gas may be introduced in a volume corresponding to 10% to 30% of the total volume of the polyurethane composition. Specifically, the inert gas may be introduced in a volume corresponding to 15% to 30% of the total volume of the polyurethane composition.

Gelation time

The composition takes a certain time until it is gelled by curing, which is referred to as a gel time.

The gelation time of the composition may be 50 seconds or more, 70 seconds or more, 80 seconds or more, and 100 seconds or more. In addition, the gelation time of the composition may be 50 seconds or more, 70 seconds or more, 80 seconds or more, and 100 seconds or more. For example, the gelation time of the composition may be 50 seconds to 200 seconds, 50 seconds to 150 seconds, 50 seconds to 100 seconds, 100 seconds to 200 seconds, and 150 seconds to 200 seconds. As a specific example, the composition may have a gelation time of 80 seconds to 130 seconds.

The gelation time may be, for example, a value measured at 70°C.

Characteristics after curing

The composition may be adjusted to a specific range of mechanical properties, such as tensile strength, elongation, hardness after curing.

For example, the tensile strength after curing of the composition is 5 N/mm ² to 30 N/mm ² , 10 N/mm ² to 25 N/mm ² , 10 N/mm ² to 20 N/mm ² , or 15 N /mm ² to 30 N/mm ² .

In addition, the elongation after curing of the composition may be 50% to 300%, 100% to 300%, 150% to 250%, or 100% to 200%.

In addition, the hardness after curing of the composition is 30 Shore D to 80 Shore D, 40 Shore D to 70 Shore D, 50 Shore D to 70 Shore D, 40 Shore D to 60 Shore D, or 50 Shore D to 60 Shore D. Can.

As a specific example, the composition may have a tensile strength of 10 N/mm ² to 23 N/mm ² after curing, an elongation of 80% to 250%, and a hardness of 40 Shore D to 65 Shore D.

The composition may have a number of fine pores after curing.

The average size of the fine pores may be 10 μm to 50 μm, 20 μm to 50 μm, 20 μm to 40 μm, 20 μm to 30 μm, or 30 μm to 50 μm.

In addition, the composition after the curing rate (removal rate) 3000 Å / 50 seconds to 5000 Å / 50 seconds, 3000 Å / 50 seconds to 4000 Å / 50 seconds, 4000 Å / 50 seconds to 5000 Å / 50 seconds, or It may be 3500 Å/50 seconds to 4500 Å/50 seconds.

In addition, the composition has a pad cut rate after curing of 30 μm/hr to 60 μm/hr, 30 μm/hr to 50 μm/hr, 40 μm/hr to 60 μm/hr, and 40 μm/hr to 50 μm/hr.

[Method of manufacturing a polishing pad]

A method of manufacturing a polishing pad according to one embodiment includes molding the composition according to one embodiment while curing.

That is, a method of manufacturing a polishing pad according to an embodiment includes preparing a first raw material composition including a urethane-based prepolymer; Preparing a second raw material composition comprising a curing agent; Preparing a third raw material composition comprising a blowing agent; Preparing the raw material mixture by sequentially or simultaneously mixing the first raw material composition with the second raw material composition and the third raw material composition; And curing by injecting the raw material mixture into a mold and curing, wherein the urethane-based prepolymer includes a prepolymerization reaction product of at least one diisocyanate monomer and at least one polyol, and the at least one diisocyanate monomer is It includes one or more aromatic diisocyanate monomers, and the urethane-based prepolymer contains 5% to 13% by weight of unreacted NCO groups based on the weight of the urethane-based prepolymer, and unreacted aromatic diisocyanate monomers. It contains 0.1 to 5% by weight.

Specifically, in the step of preparing the raw material mixture, the first raw material composition is mixed with the second raw material composition and further mixed with the third raw material composition, or the first raw material composition is mixed with the third raw material composition. After mixing, it may be performed by further mixing with the second raw material composition.

In addition, the step of preparing the raw material mixture may be performed under conditions of 50°C to 150°C, and, if necessary, under vacuum degassing conditions.

The step of injecting and curing the raw material mixture in a mold may be performed under a temperature condition of 60°C to 120°C and a pressure condition of 50 kg/m ² to 200 kg/m ² .

In addition, the manufacturing method may further include a process of cutting the surface of the obtained polishing pad, a process of processing a groove on the surface, an adhesion process with a lower layer portion, an inspection process, a packaging process, and the like. These processes can be performed in the manner of a conventional polishing pad manufacturing method.

[Polishing pad]

The polishing pad according to one embodiment includes a cured product of the composition according to the embodiment and a plurality of fine pores dispersed in the cured product.

That is, the polishing pad according to one embodiment includes a polyurethane resin and a plurality of fine pores dispersed in the polyurethane resin, the polyurethane resin is derived from a urethane-based prepolymer, and the urethane-based prepolymer is one type And a prepolymerization reaction product of at least one diisocyanate monomer and at least one polyol, wherein the at least one diisocyanate monomer comprises at least one aromatic diisocyanate monomer, and the urethane-based prepolymer has the weight of the urethane-based prepolymer. As a standard, 5% to 13% by weight of unreacted NCO group is included, and 0.1% to 5% by weight of unreacted aromatic diisocyanate monomer is included.

The polishing pad is made of a polyurethane resin, and the polyurethane resin may include a cured product (polymer) of a urethane-based prepolymer having an isocyanate end group. The weight average molecular weight (Mw) of the polyurethane resin is 500 g/mol to 1,000,000 g/mol, 5,000 g/mol to 1,000,000 g/mol, 50,000 g/mol to 1,000,000 g/mol, 100,000 g/mol to 700,000 g/ mol, or 500 g/mol to 3,000 g/mol.

The thickness of the polishing pad may be 0.8 mm to 5.0 mm, 1.0 mm to 4.0 mm, 1.0 mm to 3.0 mm, 1.5 mm to 2.5 mm, 1.7 mm to 2.3 mm, or 2.0 mm to 2.1 mm. When within the above range, it is possible to sufficiently exhibit the basic properties as a polishing pad while minimizing the variation in particle diameter of the top and bottom parts of the pore.

The specific gravity of the polishing pad may be 0.6 g/cm 3 to 0.9 g/cm 3, or 0.7 g/cm 3 to 0.85 g/cm 3.

In addition, the polishing pad, in addition to the above-described physical properties, may have the same physical properties and pore characteristics of the composition according to one embodiment before curing.

The hardness of the polishing pad may be 30 Shore D to 80 Shore D, 40 Shore D to 70 Shore D, 50 Shore D to 70 Shore D, 40 Shore D to 60 Shore D, or 50 Shore D to 60 Shore D.

The tensile strength of the polishing pad is 5 N/mm ² to 30 N/mm ² , 10 N/mm ² to 25 N/mm ² , 10 N/mm ² to 20 N/mm ² , or 15 N/mm ² to 30 N/mm ² .

The elongation of the polishing pad may be 50% to 300%, 100% to 300%, 150% to 250%, or 100% to 200%.

The fine pores are present dispersed in the polyurethane resin.

The average size of the fine pores may be 10 μm to 50 μm, 20 μm to 50 μm, 20 μm to 40 μm, 20 μm to 30 μm, or 30 μm to 50 μm. As a specific example, the fine pores may have an average size of 21 μm to 25 μm.

In addition, the fine pores may be included in 100 to 300, 150 to 300, or 100 to 250 per 0.3 cm ³ area of the polishing pad.

In addition, the total area of the fine pores may be 30% to 60%, 35% to 50%, or 35% to 43% based on the total area of the polishing pad.

In addition, the fine pores may be included in 30% by volume to 70% by volume, 30% by volume to 70% by volume, or 40% by volume to 60% by volume based on the total volume of the polishing pad.

The polishing rate of the polishing pad is 3000 Å/50 seconds to 5000 Å/50 seconds, 3000 Å/50 seconds to 4000 Å/50 seconds, 4000 Å/50 seconds to 5000 Å/50 seconds, or 3500 Å /50 seconds to 4500 4500/50 seconds. As a specific example, the polishing pad may have a removal rate of 3500 Å/50 seconds to 3900 Å/50 seconds. The polishing rate may be an initial polishing rate immediately after curing (that is, immediately after manufacturing) of the polishing pad. When the initial polishing rate is within the above-mentioned preferred range, it is advantageous to suppress a pad glazing phenomenon, thereby maintaining an appropriate level of excellent polishing rate in a subsequent repeated polishing process.

In addition, the pad cut rate of the polishing pad is 30 μm/hr to 60 μm/hr, 30 μm/hr to 50 μm/hr, 40 μm/hr to 60 μm/hr, 40 μm/hr to 50 Μm/hr.

The polishing pad may have a groove for mechanical polishing on the surface. The groove may have an appropriate depth, width and spacing for mechanical polishing, and is not particularly limited.

The polishing pad according to another embodiment includes an upper pad and a lower pad, wherein the upper pad may have the same composition and properties as the polishing pad according to the embodiment.

The lower pad serves to absorb and disperse the impact applied to the upper pad while supporting the upper pad. The lower pad may include a non-woven fabric or suede.

In addition, an adhesive layer may be inserted between the upper pad and the lower pad.

The adhesive layer may include a hot melt adhesive. The hot melt adhesive may be at least one selected from the group consisting of polyurethane-based resins, polyester-based resins, ethylene-vinyl acetate-based resins, polyamide-based resins, and polyolefin-based resins. Specifically, the hot melt adhesive may be at least one selected from the group consisting of polyurethane-based resins and polyester-based resins.

[Method of manufacturing a semiconductor device]

A method of manufacturing a semiconductor device according to an embodiment includes polishing a surface of a wafer using the polishing pad according to the embodiment.

That is, a method of manufacturing a semiconductor device according to an embodiment includes polishing a surface of a wafer using a polishing pad, wherein the polishing pad comprises polyurethane resin and a plurality of fine pores dispersed in the polyurethane resin. Included, the polyurethane resin is derived from a urethane-based prepolymer, the urethane-based prepolymer includes a prepolymerization reaction product of at least one diisocyanate monomer and at least one polyol, and the at least one diisocyanate monomer is 1 It comprises at least one aromatic diisocyanate monomer, the urethane-based prepolymer, based on the weight of the urethane-based prepolymer, contains 5% to 13% by weight of unreacted NCO groups, and unreacted aromatic diisocyanate monomer. 0.1 to 5% by weight.

Specifically, after the polishing pad according to the embodiment is adhered to the surface plate, the wafer is placed on the polishing pad. At this time, the surface of the wafer is in direct contact with the polishing surface of the polishing pad. A polishing slurry may be sprayed on the polishing pad for polishing. Thereafter, the wafer and the polishing pad rotate relative to each other, so that the surface of the wafer can be polished.

The polishing pad according to the embodiment is obtained by curing a urethane prepolymer having a controlled composition, and thus has excellent elongation, hardness, fine pore characteristics, and polishing rate, so that an excellent quality semiconductor device can be efficiently used using the polishing pad. Can be produced.

[Example]

It will be described in more detail through the following examples, but is not limited to the scope of these examples.

Examples and comparative examples

Toluene 2,4-diisocyanate (2,4-TDI), toluene 2,6-diisocyanate (2,6-TDI), polytetramethylene ether glycol (PTMEG) and dicyclohexylmethane diisocyanate (H12MDI) 4 After the reaction was performed at 80° C. by adding the flask, diethylene glycol (DEG) was further added and reacted at 80° C. for an additional 2 hours to prepare a urethane-based prepolymer.

A casting apparatus equipped with a tank and an input line for supplying raw materials such as a prepolymer, a curing agent, an inert gas, and a blowing agent, respectively, was prepared. Urethane prepolymer prepared previously, curing agent (bis(4-amino-3-chlorophenyl)methane, Ishihara), inert gas (N ₂ ), liquid blowing agent (FC3283, 3M company), solid foaming agent (Akzonobel) and silicone type Surfactants (Evonik) were charged to each tank. Through each input line, the raw materials were stirred at a constant speed into the mixing head. At this time, the prepolymer and curing agent were added in an equivalent ratio of 1:1 and a total amount of 10 kg/minute.

The stirred raw material was discharged into a mold (1,000 mm x 1,000 mm x 3 mm) and the reaction was completed to obtain a molded product in the form of a solid cake. After that, the upper and lower ends of the molded body were each cut by 0.5 mm thickness to obtain an upper pad having a thickness of 2 mm.

Subsequently, the upper pad was subjected to a surface milling and groove forming process, and was laminated with the lower pad by a hot melt adhesive.

The specific process conditions of the top pad are summarized in the table below.

division Example 1 Example 2 Comparative Example 1 Prize
part
tile
De Unreacted NCO group content of prepolymer 9.2 wt% 8.0 wt% 15 wt% Casting mold Single Single Single Sheet processing (casting, cutting, groove) Sequential Sequential Sequential Prepolymer parts by weight 100 100 100 Surfactant parts by weight 0.2~1.5 0.2~1.5 0.2~1.5 Solid foaming agent parts by weight 0.5~1.0 0.5~1.0 0.5~1.0 Inert gas input (L/min) 0.5~1.5 0.5~1.5 0.5~1.5

Test example

The urethane-based prepolymer or polishing pad obtained in Examples and Comparative Examples was tested for the following items, and the results are shown in Table 2.

(1) Prepolymer composition analysis

5 mg of the prepolymer sample was dissolved in CDCl ₃ and ¹ H-NMR and ¹³ C-NMR analysis were performed using a nuclear magnetic resonance (NMR) device (JEOL 500 MHz, 90° pulse) at room temperature. In the obtained NMR data, the peak of the reacted methyl group and the unreacted methyl group of TDI was integrated to calculate the content of the reacted or unreacted aromatic diisocyanate monomer in the prepolymer.

Specifically, when the weight of 2,4-TDI (hereinafter referred to as "4-reacted 2,4-TDI") of a polyol and urethane-reacted only NCO group substituted at the 4-position among 2 NCO groups is 100 parts by weight , 2,4-TDI in which two NCO groups are urethane-reacted with polyol to form a chain (hereinafter referred to as "2,4-reacted 2,4-TDI"), in which two NCO groups are not reacted with polyol. ,6-TDI (hereinafter referred to as "unreacted 2,6-TDI") and NCO groups substituted at the 2-position or 6-position of the 2 NCO groups, 2,4-TDI reacted with a polyol and urethane (hereinafter " 2-reacted 2,6-TDI” was calculated. (Otherwise, 2,6-TDI in which only 2-position NCO groups were reacted and 2,6-TDI in which both NCO groups were reacted were almost detected. Did not).

The results are summarized in the table below.

division Example 1 Example 2 Comparative Example 1 content
(Parts by weight) 4-reacted 2,4-TDI 100.00 100.00 100.00 2,4-reacted 2,4-TDI 36.63 49.65 13.90 Unreacted 2,6-TDI 7.83 3.65 21.22 2-reacted 2,6-TDI 21.67 26.17 9.59 Total TDI 166.13 179.47 144.71

division Example 1 Example 2 Comparative Example 1 content
(weight%)
(All TDI
By weight) Unreacted TDI 4.71 2.03 14.66 TDI with two NCOs reacted (c1) 22.05 27.66 9.61 TDI with one NCO reacted (c2) 73.24 70.30 75.73 TDI with at least one NCO reacted 95.29 97.97 85.34 c1/c2 weight ratio 0.30 0.39 0.13

division Example 1 Example 2 Comparative Example 1 Content (% by weight)
(Urethane-based prepolymer
By weight) Unreacted TDI (c3) 1.46 0.68 6.28 Unreacted H12MDI (c4) 7.60 7.60 7.60 c3 + c4 9.06 8.28 13.88 c3/c4 weight ratio 0.19 0.09 0.83

(2) Hardness

The sample was cut to 5 cm×5 cm (thickness: 2 mm), and stored at a temperature of 25° C. for 12 hours, and then Shore D hardness and Asker C hardness were measured using a durometer.

(3) Specific gravity

The sample was cut to 2 cm×5 cm (thickness: 2 mm), and stored at a temperature of 25° C. for 12 hours to measure the specific gravity of the multilayer using a hydrometer.

(4) Tensile strength

The sample was cut to 4 cm×1 cm (thickness: 2 mm), and the highest strength value just before fracture of the polishing pad was measured at a speed of 50 mm/min using a universal tester (UTM).

(5) Elongation

The sample was cut to 4 cm × 1 cm (thickness: 2 mm), and the maximum strain before the fracture of the polishing pad was measured at a speed of 50 mm/min using a universal tester (UTM), and then the maximum strain compared to the initial length The percentage of was expressed as a percentage (%).

(6) Gel time

The prepolymer and the curing agent were blended in a 1:1 ratio, and the time taken until the mixed solution stirred at 5,000 rpm was gelated at 70°C was measured.

The results are summarized in the table below.

division Evaluation item Example 1 Example 2 Comparative Example 1 Top
pad Thickness (mm) 2 2 2 Hardness (Shore D) 60 52 68 Specific gravity (g/cc) 0.8 0.8 0.8 Tensile strength (N/mm ² ) 21 18 25 Elongation (%) 125 200 63 Gelation time (s) 108 121 50 bottom
pad type Non-woven Non-woven Non-woven Thickness (mm) 1.1 1.1 1.1 Hardness (Asker C) 70 70 70 Stacked
pad Thickness (mm) 3.32 3.32 3.32 Compression rate (%) 1.05 1.05 1.05

(7) Pore characteristics

The pores of the polishing pad were observed with a scanning electron microscope (SEM) and are shown in FIGS. 1A to 1C. 1A to 1C, the pores of the polishing pads of Examples 1 and 2 were finely and uniformly distributed over a large area.

In addition, the characteristics of the pores were calculated based on the SEM image and summarized in the following table.

-Number average diameter: The average of the sum of the pore diameters on the SEM image divided by the number of pores

-Number of pores: The number of pores present per 0.3 cm ³ on the SEM image

-Pore area ratio: Percentage of the area of the pore only compared to the total area of the SEM image

division Example 1 Example 2 Comparative Example 1 Number average diameter (㎛) 22.454 23.313 20.523 Number of pores (per 0.3 cm ³ ) 176 167 162 Pore area ratio (%) 38.165 38.896 38.245

(8) Removal rate

The initial polishing rate immediately after manufacturing the polishing pad was measured as follows.

Silicon oxide was deposited on a 300 mm diameter silicon wafer by chemical vapor deposition (CVD). A polishing pad was attached to the CMP equipment, and the silicon oxide layer of the silicon wafer was installed to face the polishing surface of the polishing pad. The silicon oxide film was polished for 60 seconds at a load of 4.0 psi and a speed of 150 rpm while feeding the calcined ceria slurry at a rate of 250 mL/min on a polishing pad. After polishing, the silicon wafer was removed from the carrier, mounted on a spin dryer, washed with distilled water, and dried with nitrogen for 15 seconds. The dried silicon wafer was measured for change in film thickness before and after polishing using an optical interference thickness measuring device (SI-F80R, Kyence). Then, the polishing rate was calculated using the following equation. The results are shown in FIG. 2.

Polishing rate (Å/sec) = Polishing thickness of silicon wafer (Å) / Polishing time (sec)

As shown in Fig. 2, the polishing pads of Examples 1 and 2 had an excellent initial polishing rate at an appropriate level, whereas the polishing pads of Comparative Example 1 had an excessively high initial polishing rate due to increased aggregation of hard segments. Accordingly, the polishing pad of Comparative Example 1 is expected to sharply decrease the polishing rate due to the pad glazing phenomenon.

(9) Pad cut-rate

The polishing pad was pre-conditioned with deionized water for 10 minutes, followed by conditioning while spraying deionized water for 1 hour. The cutting rate of the polishing pad was calculated by measuring the thickness changed in the conditioning process. The equipment used for conditioning was CTS' AP-300HM, the conditioning pressure was 6 lbf, the rotational speed was 100 to 110 rpm, and the disc used for conditioning was Sasol LPX-DS2. The results are shown in FIG. 3.

As shown in FIG. 3, the polishing pads of Examples 1 and 2 had excellent pad cutting rates when conditioning using a diamond disc, whereas the polishing pads of Comparative Example 1 had poor agglomeration of hard segments, resulting in low pad cutting rates.

Claims (13)

Urethane-based prepolymer, curing agent and blowing agent,
The urethane-based prepolymer includes a prepolymerization reaction product of at least one diisocyanate monomer and at least one polyol,
The at least one diisocyanate monomer includes at least one aromatic diisocyanate monomer,
The urethane-based prepolymer, based on the weight of the urethane-based prepolymer, comprises 5% to 13% by weight of unreacted NCO groups, and 0.1% to 5% by weight of unreacted aromatic diisocyanate monomer. , Composition.
According to claim 1,
The urethane-based prepolymer, based on the weight of the urethane-based prepolymer, the unreacted NCO group comprises 7% to 10% by weight, composition.
According to claim 2,
The urethane-based prepolymer, based on the weight of the urethane-based prepolymer, the unreacted aromatic diisocyanate monomer comprises 1% by weight to 3% by weight of the composition.
The method of claim 3,
The composition, wherein the composition has a gelation time of 100 seconds to 115 seconds.
According to claim 1,
The composition, wherein the at least one aromatic diisocyanate monomer comprises toluene 2,4-diisocyanate and toluene 2,6-diisocyanate.
The method of claim 5,
The urethane-based prepolymer, based on the weight of the urethane-based prepolymer, comprises unreacted toluene 2,6-diisocyanate in an amount of 0.1% to 3% by weight.
According to claim 1,
The composition, wherein the at least one diisocyanate monomer further comprises at least one aliphatic diisocyanate monomer.
According to claim 1,
The urethane-based prepolymer, a composition comprising an unreacted aromatic diisocyanate monomer and an unreacted aliphatic diisocyanate monomer in a weight ratio of 0.05:1 to 0.7:1.
According to claim 1,
The composition has a gelation time of 80 seconds to 130 seconds,
A composition having a tensile strength of 10 N/mm ² to 23 N/mm ² after curing, an elongation of 80% to 250%, and a hardness of 40 Shore D to 65 Shore D.
Preparing a first raw material composition comprising a urethane-based prepolymer;
Preparing a second raw material composition comprising a curing agent;
Preparing a third raw material composition comprising a blowing agent;
Preparing the raw material mixture by sequentially or simultaneously mixing the first raw material composition with the second raw material composition and the third raw material composition; And
Including the step of injecting the raw material mixture into a mold to harden,
The urethane-based prepolymer includes a prepolymerization reaction product of at least one diisocyanate monomer and at least one polyol, and the at least one diisocyanate monomer comprises at least one aromatic diisocyanate monomer, and the urethane-based prepolymer is Based on the weight of the urethane-based prepolymer, the unreacted NCO group comprises 5% to 13% by weight, and the unreacted aromatic diisocyanate monomer comprises 0.1% to 5% by weight, a method of manufacturing a polishing pad .
It comprises a polyurethane resin and a number of fine pores dispersed in the polyurethane resin, the polyurethane resin is derived from a urethane-based prepolymer,
The urethane-based prepolymer includes a prepolymerization reaction product of at least one diisocyanate monomer and at least one polyol, and the at least one diisocyanate monomer comprises at least one aromatic diisocyanate monomer, and the urethane-based prepolymer is A polishing pad comprising, based on the weight of the urethane-based prepolymer, 5% to 13% by weight of unreacted NCO group, and 0.1% to 5% by weight of unreacted aromatic diisocyanate monomer.
The method of claim 11,
The fine pores have an average size of 21 ㎛ to 25 ㎛,
The polishing pad has a polishing rate of 3500 mm 3 /50 seconds to 3900 mm 3 /50 seconds.
Polishing the surface of the wafer using a polishing pad,
The polishing pad includes a polyurethane resin and a plurality of fine pores dispersed in the polyurethane resin, and the polyurethane resin is derived from a urethane-based prepolymer,
The urethane-based prepolymer includes a prepolymerization reaction product of at least one diisocyanate monomer and at least one polyol, and the at least one diisocyanate monomer comprises at least one aromatic diisocyanate monomer, and the urethane-based prepolymer is Based on the weight of the urethane-based prepolymer, the unreacted NCO group 5 wt% to 13 wt%, and the unreacted aromatic diisocyanate monomer comprises 0.1 wt% to 5 wt%, a method for manufacturing a semiconductor device .

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